基于三维热流耦合仿真的登杆电缆载流量计算

Ampacity Calculation of Vertical Tube Cable Based on Three-dimensional Heat-fluid Coupling Simulation

为分析由于外部环境突变导致的轴向传热对登杆电缆载流能力的影响,基于COMSOL Multiphysics软件建立包括裸露段、保护管段和直埋段3个区段的登杆电缆三维热流耦合仿真模型,并通过与现有模型计算结果的对比来验证所建立模型的有效性。基于该仿真模型进行分析,得到不同保护管段长度下电缆导体的轴向温度分布差异。计算结果表明:登杆电缆不同区段的导体存在较大的轴向温差,散热最好的裸露段与散热最差的保护管段稳态温差接近40℃;保护管长度对登杆电缆峰值温度和载流量影响较大,当保护管段较长时(大于7 m)在保护管段将形成温升平台,保护管长度越小峰值温度越低;所建立的模型充分考虑了不同区段间轴向传热的影响,且保护管长度越小模型的计算准确度越高,当保护管段长度为2 m时,该模型计算结果与现有模型相比最高温度降低14%。

To analyze the influence of axial heat transfer caused by the change of external environment on the ampacity of the cable installed in the vertical tube,a three-dimensional heat-fluid coupling simulation model of the cable including three sections of bare section,vertical tube section and buried section is established based on COMSOL Multiphysics software,and the validity of the model is verified by comparing its calculation results with those of the existing models.On the basis of this simulation model,this paper makes the analysis and obtains the axial temperature distributions of the cable conductor varying with different length of tube sections.The results show that there is a large axial temperature difference in the conductor between different sections,and the steady-state temperature difference between the bare section and the tube section is close to 40℃.The length of the vertical tube has a great influence on the peak temperature and amapcity of the cable.When the length of the vertical tube is longer(greater than 7 meters),a temperature rising platform will be formed in the vertical tube section,while the smaller the length of the vertical tube is,the lower the peak temperature will be.The simulation model fully considers the influence of axial heat transfer between different sections,and the smaller the length of the vertical tube,the better the improvement effect of the model compared with the results calculated by the other methods.When the length of the vertical tube is 2 meters,the highest temperature calculated by this model can be reduced by 14%compared with other models.